<div style="overflow:auto; width:120px; height:60px; background:#DDD;">
    <div style="float:right; width:130px; background:#999;">float:right</div>
</div>
<br />
<div style="overflow:scroll; width:120px; height:60px; background:#DDD;">
    <div style="float:right; width:130px; background:#999;">float:right</div>
</div>